Mechanical telephone



(No Model) 2 SheetsSheet 1.

I F. O. LUDLOW.

MECHANICAL TELEPHONE. No. 314,946. Patented Mar. 31, 1885.

2 gg 5 1m.

N0 Model.) 2 Sheets-Sheet 2.

F. G. LUDLOW.

MECHANICAL TELEPHONE.

No. 314,946. Patented Mar. 31, 1885.

WITNESSES INVENTOR a) MAM midi 1 4V" N. PETERS. Phnla-Lrlhegrnphcr.Washingou. D. c.

UNITED STATES PATENT OFFICE.

FREEMAN C. LUDLOIV, OF CINCINNATI, OHIO, ASSIGNOR TO-THE LUDLOIVTELEPHONE COMPANY, OF NEWPORT, KENTUCKY.

MECHANICAL TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 314,946, dated March31, 1885.

Application filed June 10, 1884.

To aZZ whom it nuty concern:

Be it known that I, FREEMAN C. LUDLoW, a resident of Cincinnati, in thecounty of Hanr ilton and State of Ohio, have invented certain new anduseful Improvements in Mechanical Telephones, of which the following isa specification.

The class of telephones to which my invention belongs acts upon theprinciple of the transmission of sound-vibrations through atightly-stretched wire, the vibrations being transmitted to or initiatedin the wire by a diaphragm at the speaking end, and received on asimilar diaphragm at the other end.

I 5 The principal features of novelty in my invention are, first, adevice for ringing a bell at the distant end of the line to callattention to the telephone; second, the device for connecting the tightwire to the diaphragm;

third, the device for holding the wire when the diaphragnrdoor isopened; and, fourth, a novel and useful construct-ion of the dia phragmitself.

The several features of my invention and the various advantagesresulting from their use, conjointly or otherwise, will be apparent fromthe following description and claims.

In the accompanying drawings, Figure 1 is an elevation of a verticalcentral section from front to rear of a telephone illustrating myinvention. Fig. 2 is a side elevation of the telephone, showing thebell. Fig. 3 is a front view of the telephone, the door being removed.Fig. 4 is a front view of the de- 3 5 vice, the door being present andclosed. Fig. 5 represents a top view ofthe end of the wire andconnecting parts. Fig. 6 shows the detail of the construction of thediaphragm.

Fig. 7 represents, in enlarged sectional side 40 elevation, theconstruction of the several parts, showing the levers E and I as whenconnected ready for signaling.

The telephone consists of a box or supporting-frame, A, closed by thedoor or frame B,

and which latter contains the diaphragm. The box A upholds and containscertain devices, to be more fully explained. From the top or upperportion of the box A is swung a yoke or piece, D. This yoke consists oftwo arms, (I d, and a center piece, (1 which (No model.)

has an opening, d, in the center, through which the wire passes, and isretained therein by the construction hereinafter described, and has aside piece, (1*, on each side of the opening (1, on which the wirecatches.

To the lower arm, d, a bent lever, E, is pivoted. This bent lever E hastwo arms, one of which terminates at a short distance from the back ofthe box, and when the bifurcated lever I (hereinafter described) ispushed forward this lower arm impinges against the smooth surface of theback of said box or frame-work A, which latter serves as the fulcrum ofthe lever. The other end is provided with a head, a, and a notch, e, on6 its under edge.

A strong spiral spring, G, is sprung between the arm d of yokeD and theback a of box A or equivalent support. This spring exerts its force inexpansion, and hence tends to force 0 yoke D forward; but as the yoke Dhas the wire II passing through its center piece and retained therein,it serves, in connection with a similar device at the other end of theline,to keep the wire taut.

Also swinging from the top of box A is the bifurcated lever I. Thislever consists of a handle, 1', and two arms, 1', which latter are swungfrom the top of the box A, while the former projects through the slot ain the bottom or lower portion of the box A. At the point of bifurcationthe lever I is shaped to fit into the notch c, and thus permit the leverE to catch onto the lever I, as shown in Figs.

1 and 3. Two spiral springs, K, are strained between the lever I and theback a of the box, and tend to draw the lever backward.

The preferred means of connecting the springs K to the lever I is asfollows: A vertical pin, m, is set in a projection, m, of the lever, andto the upper portion of this pin is connected the forward end of thespiral spring.

A similar construction obtains in connection with the other spiralspring K.

The door or diaphragm holder consists of a 5 frame, B, in which is anopening surrounded by a funnel-like projection, B, which serves toconvey the sound-vibrations to the diaphragm C from the person speakingto said projection. This diaphragm C is immediately berco low thisopening. The circular diaphragm C is set into the frame 13, and, asshown in Fig. 1, has only its periphery in contact with the frame, theframe being cut away or beveled fromthe periphery of the diaphragmtoward the center, substantially as shown, and leaving the diaphragmentirely free to vibrate. The door B is hinged or otherwise detachablysecured to the frame-work A, preferably at one side of the latter. \Vhenclosed, the door does not come in direct contact with the edge of thebox, but rests immediately upon rubber or other elastic blocks or piecesa". These elastic pieces prevent the vibrations imparted to thediaphragm from being dissipated by transmission to the box itself, andcompel their complete or almost complete transmission to the wire. Tofurther prevent loss of sound, as well as to avoid the introduction ofextraneous vibrations, similar rubber or elastic buttons or pieces, a,are placed between the back a of the box and the wall or lintel TV, towhich it is attached.

The wire H is provided with two hooks or projections, 71, which are partof the wire, and not merelyloosely attached to it. These hooks h loopover. or extend in front of the side pieces, at", as shown in Fig. 5.Forward of the hooks the wire H is bent slightly upward and terminatesin an eye, if, which catches over the hook c, which latter is firmlyattached to the center of the diaphragm G in any suitable manner. It ispreferably connected to the diaphragm as follows: The shank of the hookis screw-threaded, and two washers, a n, are provided with femalescrews. One washer is placed on the front side and the other at the rearside of the diaphragm. The screw-shank of the hook is screwed throughthe rear washer and through the diaphragm, and the front washer screwedonto the said shank, thereby tightly holding the diaphragm between thewashers, and securing'the hook to the diaphragm, and bracing thehook-shank so that it cannot tear out of or break the diaphragm, andalso serves to better connect all vibrations of the diaphragm to theline-wire. The wire H passes baekwardly, escaping through the opening ain the box A, and proceeds through eyes or over pulleys or loops toanother telephone of similar construction, and thus forms the line ofcommunication between these two telephones.

, On each side and on top and bottom the edge of the box or frame-workadjacent to the door is cut away, and this opening, with the spacebetween the door and box, conveniently makes the opening L, which existson both sides of the telephone, and by giving free op ening to the airin the telephone-box prevents it interfering with the vibrations of thediaphragm O.

In one corner of the'box A a block orequivalent device, M, is placed.

the block M and the side of the box A is a wire, N, the inner end ofwhich is so bent as to form two arms, a and a, the latter project-Passing through ing behind the arm (6, as shown in Fig. 3. To the outerend of the wire N the clapperwvire 0 is attached, and bent in such shapethat the clapper o is brought into proper relations with the bell P.(Shown in Fig. 2.) A spiral spring, a", encircles the wire N, and whennot compressed holds the clapper 0 in position. to receive the alarmfrom the individual from the other end of the line.

The peculiar construction of the diaphragm which I use requires specialdescription. In Fig. 6 a cross section of the diaphragm is shown. drywellseasoned wood, 0, bass or linn wood preferred. This wood is coatedwith (preferably thoroughly soaked in) shellac-varnish and allowed todry. The shellac drying on the outer surfaces and there forming a coat Idesignate by the letter 0. (See Fig. 6.) I next give the front side acoat of shellac-varnish, and while the latter is tacky I prefcrabl yplace thereon a piece of thin soft paper, 0, preferably glazed.shellac-varnish, and while the latter is still tacky applythereto apiece of thick paper, 0, preferably blottingpaper. This paper I thengive a coat of shellac-varnish, and then apply another piece oflikepaper, and I thus continue applying, alternately, acoat of varnish and apiece of paper till I have increased the thick ness of the diaphragmabout one-sixteenth of an inch.

The main advantages of such a construction of the diaphragm are thefollowing: The shellac-varnish toughcns the wood of the diaphragm andaids in preventing it from splitting. Thepaper also aidsin tougheningthedia phragm, preventing it from splitting. The varnish or gum aids inrendering the diaphragm more resonant, and also renders the diaphragmimpervious to the action of water or moisture in the air. Thus thediaphragm is at all times and seasons, and under all conditions, keptdry; and its functions are reliable and uniform, and it is always incondition to afford the best results.

"When desired, the number of layers of paper and gum on the front sideof the diaphragm may be increased at pleasure; also, when desired, thenumber of layers of gum and paper on the back side may be varied ordispensed with at pleasure but when the wooden diaphragmic piece isthin, as is preferably the ease, layers of gum and paper are preferablypresent on one or both sides of the wooden diaphragmic piece. In certainin stances, however, where the diaphragmic wooden piece, after beingcoated on one or both sides, is of sufficient strength and reso* nanceto be operative, the layers of paper and the extra layers of gum may bedispensed with.

This device of course requires a similar telephone at each end of theline, both connected with the wirein the manner heretofore de' scribed.

The method of operation is as follows: It

It consists of a plane or thin piece of I give the rear side a coat offirst necessary to ring the bell of the other I telephone to call theattention of the individual at the other end. This is accomplished bypushing the lever I backward. At the same time, in order to prevent thebell of the telephone where the person is signaling from ringing whilehe is signaling, he presses on the button, compressing the spring, andmoving the clapper toward the box A, and placing it in a vertical planelying between the box and bell. By pushing the lever I backward the freeend of the lever E is pushed or forced against the back part of the box,the lower arm of said lever being depressed by the continuance of theforce on the lever I, and its upper end or arm being raised or elevateduntil the notch c is freed from contact or connection with the leverlast named. This permits the spring G to come into play, and it throwsthe yoke D forward suddenly with some force, carrying with it the wireH. The wire II by this movement draws the cor responding yoke D in theother telephone at the other end of the line backwardly. The effect ofthis may be studied from Fig. 1. When the yoke D is forced backward, thearm d impinges against the arm a, and, through the intermediatemechanism, throws the clapper 0 rather smartly against the bell P. Thesprings K in the sending-telephone, assisted by the spring G in thereceiving-telephone, immediately return the parts to their properpositions, withdrawing the clapper from the bell,and preventing it fromdulling the sound of the hell by remainingin contact with it aftersetting it in vibration. The operator now releases his pressure on thebutton U, and the spring a expands and carries the clapper into positionto receive the signal from the other end of the line and tap theadjacent bell. The attention of the person to whom the speaker wishes totalk having been ob tained, the conversation is directed against thediaphragm O, and as the two diaphragms are connected by a tight wire thevibrations are readily transmitted, and the individual, by placing hisear to the funnel B at the other end, can hear distinctly.

\Vhen it becomes necessary to open the door of the telephone, the handle2' is drawn forward, carrying with it the yoke D. After moving forward ashort distance, the sides d of the center of the yoke catch against thehooks h, and, drawing the wire forward, lift the eye h off of the hookc. The door can now be swung open, and the interior of the telephone beinspected. This method of keeping the door and diaphragm closed avoidsthe use of extra connections between the door and the box, and thusassists in keeping the vibrations in their proper sphere.

The simplicity of the construction and the perfection of its operationmake this device one of the best extant.

Obviously, the eye h? may be substituted for the hook c on thediaphragm, and the hook a removed from the diaphragm and take the placeof eye it in the line-wire, the position of the free end of the hookbeing reversed.

In the formation of the diaphragm, instead of shellac, sandarac or othersoluble gum or gums may be substituted, and instead of the paper certainother fabrics or soft skins or other suitable substances may be used.

The various features of my invention are preferably employed together;but one or more of them may be employed without the remainder. One ormore of the features of my invention may (so far as applicable)beemployed in connection with telephones or telephonic devices otherthan those herein specificall y set forth.

hat I claim as new, and desire to secure by Letters Patent, is

1. In a telephone, the yoke-piece D, consisting of arms (1 d, andprovided with opening (1, and arm (Z being pivoted at or near its freeend, spring G, operating against arm (I, and lever'E, pivoted to thefree end of arm (1, and provided with a notch in its forward end, itsrear end being the fulcrum, and the bifurcated lever pivoted at itsupper ends, and having notch e, and handle, and springs K, substantiallyas and for the purposes specified.

2. In a telephone, the yoke-piece D, consisting of arms (Z d, andprovided with open ing (1, and the arm (I being pivoted at or near itsfree end, spring G, operating against arm d, and lever E, pivoted to thefree end of arm (2, and provided'with a notch in its for ward end, itsrear end being the fulcrum, and the bifurcated lever pivoted at itsupper ends, and having projection 19, and handle z, and springs K, andbell-crank lying across and in proximity to arm (1, to enable the latterto be operated by said arm, and clapper-shank O, clapper 0, and bell P,substantially as and for the purposes specified.

3. In a telephone, the yokepieee D, coir sisting of arms (I d, andprovided with opening (1, and the arm (1 being pivoted at or near itsfree end, spring G, operating against arm (I, and lever E, pivoted tothe free end of arm d, and provided with a notch in its forward end, itsrear end being the fulcrum, and the bifurcated lever pivoted at itsupper ends, and having projection p, and handle 2', and springs K, andbell-crank lying across and in proximity to arm (1, to enable the latterto be operated by said arm, and clapper-shank, clapper 0, bell I, knobU, and spring a, sub stantially as and for the purposes specified.

4. In a telephone, the yoke-piece D, consisting of arms (Z d, andprovided with open ing (1, and the arm (I being pivoted at or near itsfree end, spring G, operating against arm (Z, and lever E, pivoted tothe free end of arm (1, and provided with a notch, e, in its forwardend, its rear end being the fulcrum, and the bifurcated lever pivoted atits upper ends, and having projection 19, and handle 2', and springs K,and line-wire having projections or hooks 71, substantially as and forthe purposes specified.

5. In a telephone, the yoke-piece 1), consisting of arms (I d, andprovided with opening (1, and the arm (I being pivoted at or near itsfree end, spring G, operating against arm d, and lever E, pivoted to thefree end of arm d, and provided with a notch in its forward end, itsrear end being the fulcrum, and the bifurcated lever pivoted at itsupper ends, and having projection 19, and handle 7., and springs K, andline-wire having projections or hooks h and eye h and diaphragm providedwith hook c, substantially as and for the purposes specified.

6. The yoke D, having arms (1 d and center opening, d spring G,operating against arm cl, whereby the yoke is held forward, and linewirehaving projections 71, for retaining it in connection with the yoke,whereby on suitable operation the signal is operated, lever I, spring orsprings K, and the lever E, for connecting said lever I and yoke D,substantially as and for the purpose described.

7. The diaphragm 0, located in front of the box or casing, and providedwith a hook, in combination with the line-wire formed at its end with aneye and projections h, yoke D, suspended by its upper arm, (I, providedwith central opening, through which the wi re passes, and is retainedwhen disconnection of the line with the diaphragm is made, lever I, andthe intermediate lever connecting it with the lower arm of the yoke,spring G, and springs K K, all arranged to operate substantially asdescribed.

8. In a telephone, the bell, clapper, clap- I per-rod provided with rodN, operated by suitable mechanism, the rod N arranged to slidehorizontally, and the spring n for keeping the clapper in operatingplane with the bell, and yet permitting the rod N, with clapper rod Oand clapper, to be moved to one side, so that the clapper will be out ofoperating plane with the bell, substantially as and for the purposesspecified.

9. The diaph agm consisting of a wooden piece impregnated with shellac,and at rear having alternate layers of varnish and paper, substantiallyas and for the purposes specified.

10. The diaphragm consisting of a wooden piece impregnated with shellac,and at rear having alternate layers of shellac and paper, and in front alayer of shellac and paper, sub stantially as and for the purposesspecified.

11. The lever I, suspended at or near its top, and line-wire, projectionh, and eye, and hook and diaphragm, and bell and clapper, the lever Ibeing arranged in connection with yoke and its lever E, for enabling itwhen swung in one direction to connect or disconnect the line-wire andthe diaphragm, and when moved in a contrary direction to ring the bell,substantially as and for the purposes specified.

12. The diaphragm consisting of a wooden strip having alternate layersof gum and paper, substantially as described.

FREEMAN O. LUDLOW'.

itnessesz .TNo. W. Srrznnm,

O. M. HILL.

